Screw driver and wrench



May 7, 1929. A Q DECKER 1,711,520

SCREW DRIVER AND WRENCH Original Filed July ll, 1925 2 Sheets-Sheet l May 7, 1929. A. G. DECKER SCREW DRIVER AND WRENCH Original Filed July l1, 1925 2 Sheets-Sheet 2 Patented May 7, 1929.

UNITED STATES` PATENT OFFICE.

AnoNzo eALLowAY Dncxna, or BALTIMORE COUNTY, IAJIYLAND, Assrenon To Tm:

BLACK a DECKER MANUFACTURING COMPANY, or TowsoN, HABYLAND, A conf PORATION F MARYLAND.

SCREW DRIVER .AND WRENCH.

Application tiled July 11, 1995, Serial' No. 42,893. Renewed October 8, 1m.

The invention relates to a Aportable power-driven rotary tool in the form of a wrench. or screw-driver, adapted for use in setting nuts and driving bolts and screws whereby the rotary momentum of the parts 1s utllized in applylng to the Work a series of tangential hammer blows in the direction of .rotation in driving or setting' which 1n ord1nary practice is clockwise or righthanded rotation.

The tool described herein is provided with a releasing Clutch having inclined engagmg surfaces which though the may be posltively'engaged in driving t e screw or setting the nut or bolt, sllp and pass on .en-

countering an excessive reslstance, releasing the clutch and permitting the ]aws to rotate freely relatively to each other until agaln engaged. The jaws of the clutch are normally disengaged, being engaged by the pressure of the tool against the work. VV 1th exactly theright ratio of pressure to resistance on the part of the work, the clutch is, when the screw or nut approaches set or final position, repeatedly released and engaged, permitting the .rotary parts of the tool to generate sufficient momentum between each such engagement of the Jaws to apply to the chuck and bit or the driven end of the tool when the jaws re-engage 1n each instance, a hammer blow in a tangential direction tending to set the nut, screw or bolt. The repeated release and engagement of the jaws produces a series of hammer blows delivered in quick succession at substantially regular intervals. The screws, nuts and bolts are thus set from one and a half to three or four turns tighter than in f the-ordinary operation of the tool.

Preferably the jaws are made of specially hard steel to resist this treatment, and the method-:pf driving screws and setting nuts and bolts described, has been widely taught by'. applicants salesmen and officers, and has become general practice among applicants customers.v The greatly increased eiiiciency of operation obtained by this method and apparatus is recognized. The only dificulty 'encountered is the reduced life of the parts. The shock andA vibration due to the operation described is regarded bythe motor manufacturers as injurious to the motor, and it has been suggested that there is a tendency to destroy the gears and other connections, correspondingly -reducing their period of useful operation.

The object of the present invention is to reduce and overcome the diflculty thus presented. To this end the applicants have produced andV devised a new and improved power-driven rotary tool in the form of a wrench and screw-driver particularly adapted for use in setting nuts,.bolts and screws by ratcheting in as described, the tool having the improved clutch teeth'adapted to resist the wear and shocks to which they are subject in this operation, and having inclined surfaces which pass on encountering a resistance greater than that tending to hold them in engagement, a train of gearing connecting the spindle to the motor and a flexible coupling at any convenient point between the spindle and the motor. This must be distinguished from a friction clutch intended to yield by slipping. It is a bona [ide iexibleconnection so devised that it yields slightly to any and every `shock passed through the train of Connections. It does rotslip or in any way change the gear ratio or introduce any frictional element Ior any lost'motion beyond a slight degree of yield at the instant of each shock, which yielding motion is later taken up. The invention contemplates the use of such yielding coupling in combination with a releasing clutch having teeth of Iexceedingly tough metal with-A extremely hard surfaces adapted for use in the ratchet-4 ing in operation vdescribed and for any power-driven portable rotary tool having a releasing clutch providing for positive or substantially positive intermittent engagement of the motor with the work, the flexible coupling being between the spindle and the motor, and preferably between the spindle on one side and the gearing and motor on the other side, protecting the motor and preferably the motor and gearing from the shock incident to the engagement of the clutch.

In the accompanying drawing I have illustrated a portable rotary power-driven pressure is applied to the tool, until the ratio of resistance to pressure applied is increased beyond a certain-point determined by the angle of the teeth, the same being in combination with a flexible coupling between the spindle on one side and the motor and gearing on the other side.

l In the drawings- Figure 1 is a vertical central section on the axis of a ortable rotary power-driven tool of the ype previously defined, the Gears, motor, etc. being shown in elevation. he said section is taken on the line 1-1 of Figure 2, but slightly distorted for convenience of illustration.

Figure 2 is a section on the line 2, 2 of Fig. 1.

Figure 3 is a bottom plan of the flexible coupling.

Figure 4 is a side view of the same.

Figure 5 is a view of the driving coupling member, the driven member being removed for convenience of illustration.

Referring to the drawings by numerals, each of which is used to indicate the same or silnilar parts in the different figures; the portable power-driven wrench or screwdriver shown comprises a casing 1 in which is mounted a motor 2, a. spindle 3, a train of reducing gearing to be described, connecting the motor shaft 5 to the spindle, a toolholding chuck 8, chuck shaft 9 and releasing toothed clutch 10. The train of reducing gearing as shown comprises a inion 34 on the motor shaft, a spur gear 33 riven thereby, a 1pinion 32 carried by and rotating with tie gear 33, a gear 31 meshing with and driven by the pinion 32, a pinion 30 rigidly connected to and rotating with the ear 31, the pinion 30 meshing with and drivin the gear 18, which is an element of the exible coupling to be described. The clutch 10 is normally released by a spring 11 and provided with teeth 12 on the chuck shaft and 14 on the spindle, which are formed of the hardest and toughest metal obtainable and provided with excessively hard inclined engaging surfaces 15, 16, which cause the clutch to release whenever the bit encounters a resistance which is suiciently great in proportion to the pressure applied to the tool to cause the clutch members to slip one by the other, the said ressure of the tool against the work tendmg to hold the teeth in engagement, and the resistance to the rotary moment tendin to slide the teeth one by the other and re ease the clutch. The flexible coupling ma be placed at any preferred point. As s own the end gear 18 of the train of reducing gears, is formed on the -llexible coupling 20, the gear teeth being formed on the outer periphery of the casing 21 of the couplin which casing also forms one element of t e coupling, which element or casing 21 carr ing the teeth 19 of the gear 18 rotates freel7 on the reduced end 22 of the spindle 3. he other element 24 of the coupling is a smaller disc-like member keyed to the spindle 3 by a key member 23 to rotate therewith. This coupling member or element 24 which is concentric with the spindle and w'ith the gear 18, fits inside the casing 21 and is secured to the gear 18 by means of pins 25 which are parallel to the axis spaced out wardly from the centre and spaced apart from each other by a suitable distance. These pins are of flexible material as raw hide or the like, and each pin is seated in a suitable hole 26, 27 in each of the members connected, and these members, i. e., the disc 22 and the gear 18, are so formed as to provide an annular chamber or space 28 between the members 24 and 18, and including the intermediate portion of each of the pins 25, providing for 'the lateral flexing of the pins and hence for a slight yielding of the disc 24 relatively to the gear 18, which yield is almost immediately recovered and though it is sufficient to take up the shock on the gearing and motor incident to repeated engagement of the toothed clutch 9, it does not provide any considerable degree of lost motion resulting in friction and loss of power or uncertainty of operation of any sort.

In this way the life of the motor and gearing is indefinitely increased without loss of the positive operation of the tool, Without greatly increased expense of construction and without loss of power by slipping and by friction, and without loss of the desired degree of precision.

The oieration is obvious from the descri tion an drawing. The drive is from t e motor shaft through pinion and gears 34, 33, 32, 31 and 30 to the gear 18, which forms part of the coupling, and by Way of flexible pins 25 to the disc 24, which is also art of the flexible coupling which is secure( to the spindle and which drives the chuck and blt by way of the ratcheting in clutch 10.

I have thus described specifically and in detail a single embodiment of my invention in order that the nature and operation of the same may be clearly understood; however, the specific terms herein are used descriptively rather than in a limiting sense, the scope of the invention being detined in the claims.

What I claim and Letters Patent is:

1. In a rotary power-driven portable tool a motor, a spindle with a releasing toothed clutch which is closed by the pressure of the tool upon the work, a coupling composed of two members, one connected to the spindle, the other to the motor, and ielding means connecting said members for imited relative yielding motion.

2. The combination in a portable powerdriven rotaryl tool, serving as a wrench or desire to secure by screw-driver of a toothed clutch having hardened inclined en aging surfaces adapted for ratcheting in as erein described, and a spindle and tool holder intermittently connected by said clutch, a 'motor and a coupling composed of two members, one having a positive driving connection to the spindle, the other having a positive connection from the motor and yielding means connecting said coupling members for limited rotation one relatively to the other.

3. The combination in a portable powerdriven rotary tool, of a toothed clutch having hardened inclined engagin surfaces adapted for ratcheting in as herein described, and a spindle and tool holder intermittently connected by said clutch, a motor and a coupling composed of two members, one having a positive driving connection to the spindle, the other having a positive connection to the motor and yielding means connecting said coupling members for limited rotation one relatively to the other, the oo nnections from the motor to the coupling including a train of reducing gears, one of which gears is formed on the coupling.

4. The combination in a ortable powerdriven rotary tool, of a toot ed clutch having hardened inclined engaging surfaces adapted for ratcheting in as herein described, and a spindle and tool holder intermittently connected by said clutch, a motor and a coupling composed of two members,

one having a positive driving connection to the spindle, the other having a positive driving connection to the motor and yielding means connecting said coupling members for limited rotation one relatively to the other, the yielding connection comprising a series of flexible pins substantially parallel to the axis, each said pin being seated in its respective ends in each of said coupling members, and the coupling having a chamber enclosing the intermediate portion of the pins providing for a limited yielding of one coupling member relatively to the other. 5. The combination in a portable powerdriven rotary tool of a spindle and chuck, a motor and a coupling, composed of 1two members, one having a positive driving connection to the spindle, the other having a positive connection to the motor and yielding means connecting said coupling members for limited yielding of one relatively to the other.

6. In a rotary, a power-driven, portable tool, a motor, a bit holder, a releasing toothed clutch which is closed by the pressure of the tool upon the work, two members, one connected to the bit holder, the other to the motor, and means yielding to the torque of the tool connectingsaid members for limited relative yielding motion.

Signed by me at Baltimore, Maryland, this 8th day of July, 1925.

ALONZO GALLOWAY DECKER. 

